A Russian special forces commander served on four battlefronts across eastern Ukraine after joining Russia’s invasion nearly three years ago. He said the most ferocious fighting he has seen is now unfolding back home, as the Russian Army he serves struggles to liberate a sliver of national territory from Ukrainian forces.

The protracted battle for the occupied Russian town of Sudzha and the surrounding countryside has unexpectedly emerged as one of the focal points of a war fought over the fate of the Ukrainian state. Both sides have committed a significant share of their limited reserves to control Sudzha, a once sleepy county seat in the Kursk region, near the two countries’ border.

“These are the most brutal battles — I haven’t seen anything like this during the entire special military operation,” the commander, who leads about 200 men fighting in Kursk, said in an interview near the front line late last year, using the Kremlin’s euphemism for the war. He requested that he be identified only by his call sign,Hades, according to military protocol.

Both sides see Kursk as must-have territory, an important element in the expected peace talks promised by President Trump. Military analysts say the Ukrainian forces have since poured some of their best reserves into Kursk, hoping to use its conquest as a bargaining chip in negotiations.